1. Field of the Invention
This invention deals with boronating organic compounds particularly those which are useful in lubricant compositions.
2. Description of the Art
Boron is a desirable ingredient for inclusion in lubricant compositions. The boron functions to protect metal surfaces apparently by forming a barrier between the metal surfaces which is effective to prevent scuffing and scraping. It is also extremely desirable in a lubricating composition or in the manufacture of an additive for a lubricating composition to have a product which incorporates the boron in a fully soluble or dispersible form within the lubricant. It is also desirable that the boron-containing compound or complex be clear to allow optical screening of the components for contaminants.
U.S. Pat. No. 4,328,113, issued May 4, 1982 to Horodysky et al, discloses that borated derivatives may be prepared by treating amines or diamines with boric acid in the presence of an alcoholic or hydrocarbon solvent. It is further stated that the presence of the solvent is not essential and it desired that the solvent be a non-reactive material such as isopropanol, a butanol or a pentanol.
Klass et al, in U.S. Pat. No. 3,000,916, issued Sept. 19, 1961, discloses that a tallow-derived propylene diamine may be reacted with a polymeric linoleic acid to form a hazy product. This product is then reacted with boric acid in methanol, followed by the addition of a hydrocarbon diluent oil, and thereafter having the entire reaction mixture stripped.
Malec, in U.S. Pat. No. 4,426,305, issued Jan. 17, 1984, teaches that the dispersancy of a lubricating oil is improved by the combination of (a) a boronated hydrocarbon-substituted succinic amide/imide/ester of an oxyalkylated amine and, (b) a Mannich condensation product of a hydrocarbon-substituted phenol, formaldehyde or amine, optionally including therein a fatty acid or boronating agent. Products having a boron content of 0.49%, are stated by Malec to be obtained from the reaction of a polyisobutenyl succinic anhydride with an oxyethylated polyethylene amine. The amine is said to be treated with boric acid and water in a 3:1 respective weight ratio. Malec teaches the resultant products as having a relatively low boron content and to give a clear, boronated succinimide dispersant.
Burt et al, in U.S. Pat. No. 3,322,670, issued May 30, 1967, describes the combination of an alkenyl substituted succinic anhydride, boric acid, boric acid anhydride or a boric acid ester, either as a solid or as a solution in a solvent such as dioxane, acetone or methanol or as a suspension in a light hydrocarbon oil. It is further stated by Burt that it is advantageous to employ as an aid for the combination a hydroxylic compound such as water or a lower (C.sub.1 to C.sub.4) alkanol such as methanol, ethanol, propanol, isopropanol, N-butanol, isobutanol and the like or mixtures of water with any one of the alcohols.
Piasek et al, in U.S. Pat. No. 3,703,536, issued Nov. 21, 1972, teaches that a boron to nitrogen weight ratio of 1.2:1 may be obtained in a di(alkenylsuccinimide) of N.sub.1,N.sub.3 -symmetrical bis (aminopolyazalkylene) urea. The boronation is conducted by stirring a solution of the aforementioned component, heating it to 100.degree. C., and adding in a slurry of boric acid in a 5W oil. Water is then added and the resulting stirred mixture heated to 138.degree. C. and held at that temperature. Nitrogen gas is then injected into the hot liquid until all water and added water (about 1.5 moles of water per mole of the boric acid employed) is driven off. The boron content of the product is stated to be 2.5%.
LeSuer, in U.S. Pat. No. 3,087,936, issued Apr. 30, 1963, teaches that the reaction of acylated nitrogen compositions with boron compounds can be effected by simply mixing the reactants at the desired temperature. An inert solvent is optionally included in the LeSuer reaction, especially when a highly viscous or solid reactant is present in the reaction mixture. The inert solvents of LeSuer may be a hydrocarbon such as benzene, toluene, naphtha, cyclohexane, n-hexane or mineral oil. It is further taught by LeSuer that water may be removed from the reaction mixture as it is formed.
Davis et al, in U.S. Pat. No. 4,119,552, issued Oct. 10, 1978, teaches that organic materials may be boronated and that any excess boronating agent may be removed by standard means such as filtration, or by washing with water, alcohols or mixtures thereof. It is further suggested when a solid is employed in the boronation reaction that hydrocarbons such as hexane, octane, nonane, toluene, xylene, mineral oil and the like be employed. Davis et al also allow for the use of chlorinated hydrocarbons as solvents including chlorobenzene, dichlorobenzene and the like.
U.S. Pat. No. 4,533,481, issued Aug. 6, 1985 to Jahnke discloses that inhibitors which comprise mixtures of monoamine salts of polycarboxylic acids and boric acid may be used to prevent the corrosion of metal surfaces contacting aqueous systems. Jahnke contemplates the use of mixtures comprising 15-30% by weight of a polycarboxylic acid, 5-20% by weight of a boron acid, 40-55% by weight of a monoamine and the remainder is water. It is further stated that generally from 10-30% by weight of the mixture is water.
U.S. Pat. No. 4,554,086 to Karol et al, issued Nov. 19, 1985, teaches that lubricating oils of an improved wear resistance and dispersancy are obtained containing borate esters of hydrocarbyl-substituted mono- and bis-succinimides containing polyamine chain linked hydroxyacyl groups. Karol teaches that the boric acid is added to his reaction mixture (to be boronated) as a 5-50% weight slurry in a diluent oil. Karol further states that the water of reaction is removed as it is formed.
It is, therefore, desirable to find a manner to effectively incorporate boron into a compound containing an amine group or a salt thereof wherein the compound also contains an amide, imide or Mannich based structure. It is desirable to chemically incorporate as much boron as possible to obtain a clear solution and a high degree of stable boron in the product. The boron is desirably a part of the amine compound and not present as a inorganic polyborate salt. It is further desirable to obtain a fast and efficient method of incorporating the boron into the reaction product without removing the water of reaction as it is formed.
The present invention deals with the foregoing goals as hereinafter described. Throughout the specification and claims, ratios and percentages are by weight, temperatures are in degrees Celsius and pressures are in Kpa gauge, unless otherwise indicated. References to patents and literature articles cited herein are incorporated by reference.